Percutaneous aspiration catheter system

ABSTRACT

A percutaneous aspiration catheter removing thrombus or other emboli from blood vessels and a method of extracting embolus pieces larger than the diameter of the catheter. The percutaneous aspiration catheter has barbs positioned near its end to trap material within the catheter.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation in part of U.S. patent application,Ser. No. 08/449,203 filed on May 24, 1995 now U.S. Pat. No. 5,827,229and entitled PERCUTANEOUS ASPIRATION THROMBECTOMY CATHETER SYSTEM, theentire disclosure of which is hereby incorporated by reference.

FIELD OF THE INVENTION

This invention relates to a device used to break up and extract bloodclots or thrombi which form within blood vessels. More particularly,this invention relates to a device adapted to break up and extract clotsor thrombi which may form within a coronary artery comprising animproved percutaneous aspiration thrombectomy catheter system.

BACKGROUND OF THE INVENTION

Approximately 1.2 million Americans suffer heart attacks each year. Alarge percentage of the heart attacks are caused by blood clots orthrombi which form within the coronary arteries. A thrombus is nature'sway of stemming the loss of blood from its pipeline system by corkingoff an opening into the vascular tree. The biochemical process whichresults in thrombus formation is not fully understood. However, insimple terms, injury to the vascular wall releases chemicals which leadto conversion of soluble, circulating fibrinogen molecules into apolymeric structure of fibrin. The fibrin structure is insoluble andarranges itself into a three dimensional network of meshed strands whichentraps red blood cells. The individual strands are approximately 0.2microns in diameter and the mesh size is approximately 1 micron.Accordingly, five micron red blood cells are easily trapped within thethree dimensional "net".

When a thrombus forms, it effectively stops the flow of blood throughthe zone of formation. If the thrombus extends across the interiordiameter of an artery, it cuts off the flow of blood through the artery.If one of the coronary arteries is 100% thrombosed, the flow of-blood isstopped in that artery resulting in a shortage of oxygen carrying redblood cells to supply the muscle (myocardium), of the heart wall. Such athrombosis is unnecessary to prevent loss of blood but can beundesirably triggered within an artery by damage to the arterial wallfrom atherosclerotic disease. Thus, the underlying disease ofatherosclerosis may not cause acute-oxygen deficiency (ischemia) but cantrigger, acute ischemia via induced thrombosis. Similarly, thrombosis ofone of the carotid arteries can lead to stroke because of insufficientoxygen supply to vital nerve centers in the cranium. Strokes can also becaused by an embolus which has formed and then is dislodged from anupstream blood vessel or the heart itself. It is carried by flowingblood to a vessel supplying the brain where it lodges in the vessel,blocking the blood flow and triggering a stroke. These emboli mayconsist of thrombus, atheroslerotic plaque or a combination of the two.They are typically older and harder than fresh thrombus and resist theaction of thrombolytic drugs.

Oxygen deficiency reduces or prohibits muscular activity, can causechest pain (angina pectoris), and can lead to death of myocardium whichpermanently disables the heart to some extent. If the myocardial celldeath is extensive, the heart will be unable to pump sufficient blood tosupply the body's life sustaining needs. The extent of ischemia isaffected by many factors, including the existence of collateral bloodvessels and flow which can provide the necessary oxygen.

Coronary artery bypass graft (CABG) surgery is a surgical method forbypassing coronary arteries which, because of narrowing or obstruction,are unable to supply adequate oxygen to heart muscle. In recent years,direct administration of chemical lysing agents into the coronaryarteries has shown to be of some benefit to patients who have thrombosedcoronary arteries. In this procedure, a catheter is placed immediatelyin front of the blockage and a drip of streptokinase is positioned to bedirected at the upstream side of the thrombus. Streptokinase is anenzyme which is able in time to dissolve the fibrin molecule. Thisprocedure can take several hours and is not always successful inbreaking up the thrombus. Furthermore, it can lead to downstreamthrombus fragments (emboli) which can lead to blockage of small diameterbranches. Auth, U.S. Pat. No. 4,646,736, discloses a thrombectomy devicethat permits rapid removal of an obstructive thrombus. However, thedevice is characterized by small catheter tip size and thus is unable toexert significant total force on clot masses. Also, a clot which is notin good position of purchase on a vessel wall in the "line of fire" ofthe rotating wire is not fibrinectomized. This is especially true ofclots floating free in the blood stream, since it is virtuallyimpossible to revolve within these clots in the absence of a constraintsuch as fingers.

Further disadvantages to this thrombectomy device include the difficultyof keeping the clot in the space above the wire during all degrees ofrotation as the wire is moved sideways during rotation, which issometimes necessary to sweep the arterial lumen. In fact, sweeping outan entire arterial lumen with a rotating wire is virtually impossible inall but the smallest, i.e., less than 1.5 mm diameter, arteries. Anadditional and serious possible disadvantage is that fragments of theclot may be embolized downstream.

Therefore, there has been a definite need for a thrombectomy device thatcan be more effective in sweeping arteries, in removing emboli that arefree floating or not perfectly positioned, and in minimizingfragmentation of clots. These and other objects of the invention willbecome apparent from the following discussion of the invention

SUMMARY OF THE INVENTION

The present invention provides for an improved system for removingthrombus from blood vessels which includes the following components:

a catheter having proximal and distal ends, designed to be advancedthrough a hemostasis valve and guide catheter and over a guide wire forplacement of its distal end at the thrombus, the catheter having atleast one lumen passing from the proximal to the distal end;

the catheter having a guide wire retaining means, which retains theguide wire within the catheter in a peripheral or non-centered part ofthe catheter cross-section. The distal tip of the catheter is angledback from the guide wire retaining means to allow the catheter to easilyfollow the guide wire around tight bends and across restrictions;

suction means in fluid communication with the proximal end of thecatheter for providing vacuum down the catheter lumen to the distal tip,for drawing thrombus into the lumen; and

the lumen terminating in and angled tip at the distal end of thecatheter, the angled tip improving the removal of thrombus adhering tothe vessel wall and reducing clogging of the hole with thrombus.

In another embodiment of the present invention, an improved thrombectomycatheter and method of use is disclosed. The catheter has barbs locatednear the distal end. The barbs may be attached to the catheter orintegrally formed with a radio opaque ring and thereby also serve as amarker band. The ring may have a reverse bend which provides a channelto retain a guide wire. The barbs provide safety in that any particlesentering the catheter can not float out. The barbs further provide ameans of removing pieces of thrombus which are larger than the diameterof the catheter and which may be too hard to deform or break apart andbe drawn through the catheter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a bifurcated blood vessel havinga blunt tip catheter and guidewire inserted at the point of bifurcation;

FIG. 2 is a schematic representation of a bifurcated blood vessel havinga catheter with an unconstrained angled tip and guidewire insertedtherein at the point of bifurcation;

FIG. 3(a) is a schematic representation of a bifurcated blood vesselhaving a constrained angled tip catheter and guidewire inserted at thepoint of bifurcation with the angled tip of the catheter in oneorientation;

FIG. 3(b) is a schematic representation of a bifurcated blood vesselhaving a constrained angled tip catheter and guidewire inserted at thepoint of bifurcation with the angled tip of the catheter in anotherorientation;

FIG. 4 is a schematic representation of a preferred embodiment ofpercutaneous aspiration thrombectomy catheter system. according to thepresent invention;

FIG. 5(a) is a schematic representation of a preferred embodiment of apercutaneous aspiration thrombectomy catheter system according to thepresent invention with a two lumen configuration;

FIG. 5(b) is a cross-section of the percutaneous aspiration thrombectomycatheter depicted in FIG. 5(a);

FIG. 5(c) is another cross-section of the percutaneous aspirationthrombectomy catheter depicted in FIG. 5(a);

FIG. 6(a) is a schematic representation of the tip design of a singlelumen percutaneous aspiration thrombectomy catheter according to thepresent invention showing a variation wherein the distal tip is punchedto provide a hole through which the guidewire is inserted;

FIG. 6(b) is a plan view of a schematic representation of the distal tipdepicted in FIG. 6(a);

FIG. 6(c) is a side view of the distal tip depicted in FIG. 6(a) priorto the formation of the bent tip;

FIG. 6(d) is an end view of the distal tip depicted in FIG. 6(c);

FIG. 7(a) is a cross-sectional representation of a single lumen designof a necked down distal tip for a percutaneous aspiration thrombectomycatheter depicted in FIG. 5(a) showing the location of the proximalentry of the guidewire at the distal exit point of the guidewire;

FIG. 7(b) is a longitudinal cross-section of the single lumen design fora necked down distal tip for the percutaneous aspiration thrombectomycatheter shown in FIG. 7(a) without the insertion of the guidewire;

FIG. 7(c) is a side view of the single lumen design for necked downdistal tip for the percutaneous aspiration thrombectomy catheter shownin FIG. 7(a) without the insertion of the guidewire;

FIG. 7(d) is a distal end view of the embodiment shown in FIG. 7(c);

FIG. 8 is a cross-sectional representation of a single lumen off-set tipdesign for the percutaneous aspiration thrombectomy catheter accordingto FIG. 5(a) showing a distal guidewire exit hole and a thrombus entryport located in the off-set section of the distal tip;

FIG. 9(a) is a schematic representation of the tip design of a preferredembodiment of a percutaneous aspiration thrombectomy catheter systemaccording to the present invention with a two lumen configuration and abarb with two points attached to the catheter tip with the barb pointsoriented distally;

FIG. 9(b) is a plan view of the barb depicted in FIG. 9(a);

FIG. 10(a) is a schematic representation of the tip design of apreferred embodiment of a percutaneous aspiration thrombectomy cathetersystem according to the present invention with a two lumen configurationand a cutting-blade attached to the catheter tip with the bladebisecting the thrombus aspiration lumen;

FIG. 10(b) is a plane view of the blade depicted in FIG. 10(a);

FIG. 10(c) is an end view of the distal tip depicted in FIG. 10(a);

FIG. 11(a) is a schematic representation of the tip design of apreferred embodiment of a percutaneous aspiration thrombectomy cathetersystem according to the present invention with a two lumen configurationand an expandable balloon attached to the catheter tip-near to thedistal end; and

FIG. 11(b) is a cross-sectional representation of the distal tipdepicted in FIG. 11(a).

FIG. 12(a) is a partially cross-sectioned side view of anotherembodiment of the percutaneous aspiration thrombectomy catheter system.

FIG. 12(b) is an end view of the embodiment of FIG. 12(a).

FIG. 13 is a partially cross-sectioned side view of another embodimentof the percutaneous aspiration thrombectomy catheter system.

FIG. 14(a) is a partially cross-sectioned side view of furtherembodiment of the percutaneous aspiration thrombectomy catheter system.

FIG. 14(b) is an end view of the embodiment of FIG. 14(a).

DETAILED DESCRIPTION OF THE INVENTION

According to the invention, a system for removing thrombus from bloodvessels comprises a catheter having proximal and distal ends, designedto be advanced through a hemostasis valve and guide catheter and over aguidewire for placement of its distal end at the thrombus, the catheterhaving at least one lumen passing from the proximal to the distal end,and a guidewire retaining means, which retains the guidewire within thecatheter in a peripheral or non centered part of the catheter crosssection. The distal tip of the catheter is angled back from theguidewire retaining means to allow the catheter to follow the guidewirearound tight bends and across restrictions easily. Also, there issuction means in communication with the proximal end of the catheter forproviding vacuum down the catheter lumen to the distal tip, for drawingthrombus into the lumen, and the lumen terminates in the angled tip atthe distal end, the angled tip improving the removal of thrombusadhering to the vessel wall and reducing clogging of the hole withthrombus.

Various prior art references on thrombectomy aspiration cathetersaddress the use of plain, single lumen catheters with a blunt tip over aconventional guidewire. In some cases the catheters taught there mayhave side holes (such as, for example, drug infusion catheters).In-vitro testing has established that single lumen, round bore cathetersneed to be at least 0.042" i.d. to effectively remove a thrombus with a0.009" guidewire down the middle. When such catheters were placed in a"heart model", it was found that it was sometimes very difficult tomaneuver such a catheter over the wire at a bifurcation. The blunt tiptended to advance straight and would catch at the bifurcation. Adding anangled tip to the catheter helped in negotiating the bend if the tip wason the inner radius of the curvature. If it was on the outside, itincreased the tendency to snag at the bifurcation. As will be seen,adding a means to capture the guidewire on one side of the catheter andtapering from that point made it possible to always negotiate a rightbend or bifurcation.

Vacuum is provided using a small diaphragm pump which maintains a steadyvacuum of about 550 millimeters of Mercury vacuum. The use of a pumpmakes it easy to advance the catheter tip through the thrombus with asteady vacuum level. Most of the previous clinical use of thrombectomycatheters used suction applied with a syringe, It has been found that itis difficult to advance the catheter while maintaining steady vacuumwith the syringe.

The angled tip provided for in the present invention provides a greatercross-sectional area for the thrombus to enter the catheter, increasingthe total force (Force=Pressure X Area) which is applied to thethrombus, increasing the amount and rate of thrombus removal andreducing the tendency to clog.

Various additional features are contemplated and may be optionallyincorporated into the device of the present invention to improve itsoverall efficiency and workability. For example, an exit point for theguidewire allows the guidewire to continue outside of the catheter inthe proximal section, allowing the catheter and guidewire to separatelypass through the hemostasis valve.

It has been found that optimal tracking of the relatively large borethrombectomy catheter over the small guidewire works best if the wire isheld at the outer wall of the catheter tip and the tip is angled backfrom that point. However, to simplify sealing around the guidewire it isgenerally easiest if the guidewire and catheter are passed through thehemostasis valve separately. This eliminates the need for a separateseal around the guidewire at the proximal end of the catheter. This isadvantageous, as was shown when an embodiment of the present inventionwas tested with a seal at the proximal end of the catheter through whicha guidewire was passed. To advance the catheter over the guidewire withthe vacuum on, the guidewire seal had to be loosened. Air wasimmediately pulled through the seal and into the catheter and rapidlyfilled the blood collection bottle. Also, there was a lower level ofvacuum in the inner lumen at the catheter tip. The presence of air inthe catheter can also be a problem if it is desired to infuse medicantsthrough the catheter.

Since coronary thrombi are often initiated by a lesion on the vesselwall, it is sometimes advantageous to dilatate the lesion with a ballooncatheter, thereby reducing the constriction and reducing the chances foranother thrombotic event. Many examples of these devices are known tothe art. To facilitate this dilatation procedure, an expandabledilatation balloon may be incorporated integral to thrombectomy catheterat or near the distal tip. This allows the operator to easily dilatatethe lesion before or after aspirating the thrombus utilizing a singledevice.

A situation occasionally occurs when a large, very firm thrombus isaspirated into a catheter tip but is not fragmented and withdrawn downthe catheter. In this situation, there is a need to positively retainthe thrombus within the catheter tip. To accomplish this a barbincorporating one or more-points can be placed within the catheter lumenat the distal tip. By orienting the points proximally, the thrombus iseffectively retained and prevented from escaping.

Another way to handle this situation is to place a blade within thedistal tip of the catheter lumen with the sharp edge facing distally.The blade cuts the large thrombus and allows the pieces to more easilypass through the catheter lumen.

A bottle or bag may be provided between suction means and the catheterfor collecting blood and thrombus as it is removed by the suction means.Further, a filter may be provided between the suction means and thecatheter to separate the solid thrombus from the liquid blood, saidfilter preferably being located-within the collecting bottle. The filterprovides a convenient way to visualize the amount of clot removed andmakes it easy to take a sample for analysis.

A guidewire retaining means may be provided, comprising a second lumenextending proximally from the distal end of the catheter, terminatingprior to the point where the catheter passes through the hemostasisvalve.

A variation of the device of the present invention wherein the guidewireretaining means comprises a second lumen has both advantages anddisadvantages. Advantages include:

no holes penetrating through the main aspiration lumen to reduce vacuumto the tip and suck additional blood through; and

slight ease in loading the catheter on the guide wire.

A "partial rapid exchange" design can be accomplished using a longguidewire lumen with a slit from the proximal end, extending to severalinches (less than 10 cm) from the distal end. The cardiologist user canload the catheter over the short rapid exchange length guidewire andinsert both the wire and catheter through the guide sheath to thecoronary arteries. At that point, the guidewire extends distally out ofthe catheter and through the thrombus. The catheter is then advanced. Toremove the catheter, it is withdrawn over the wire to the point wherethe guidewire lumen is exposed and then the catheter is peeled off ofthe guidewire as it is withdrawn to the end of the slit. The last twoinches are then pulled off. At this point another rapid exchangecatheter can be advanced over the guidewire but not another thrombectomycatheter. Of course, the thrombectomy catheter can be used with anystandard length guidewire.

The main disadvantage of the two lumen design is that a slightly largerdiameter is required due to the presence of the added internal wall.

The proximal end of the second guidewire lumen may be provided with aslit for a portion of its length from the proximal end toward the distalend to allow for the peeling of the catheter from the guidewire, as thecatheter is removed from the vasculature over the guidewire. Also, thedevice of the present invention may be configured as a single lumencatheter where the guidewire retaining means is comprised of two holesin the lumen, one at the distal end and one intermediate between thedistal and proximal ends allowing the guidewire and catheter to passseparately through the hemostasis valve.

This latter design is the simplest to manufacture but it has somefunctional problems as described above for the double lumenconfiguration.

The end of the catheter can be necked down for a distance before theguidewire exit hole at the distal end of the catheter. The reason forthis necking down is that it allows the guidewire to be retracted intothe catheter without losing placement in the guidewire hole. Thistechnique is often used when the cardiologist is initially inserting theguidewire and catheter through the hemostasis valve. Retracting theguidewire into the catheter protects the delicate guidewire tip whileadvancing across the hemostasis valve which can damage the tip ifexposed.

The distal end of the catheter may be offset from the catheter centerline, improving the removal of thrombus adhering to the vessel wall whenthe catheter is rotated around the guidewire. This is an improvementwhich may be incorporated into a catheter intended for use in largervessels. Reinforcing the wall of the catheter with metal or plasticbraid substantially increases the torsional strength and kink resistanceof the catheter yet maintains longitudinal flexibility for placement ofthe catheter within tortuous vessels.

The suction means may be attached to the catheter with tubing, the sizeand length of said tubing being selected to reduce the flow of blood dueto friction flow losses, reducing blood removal from the patient withoutbecoming clogged from aspirated thrombus particles. This concept wasdemonstrated, by using a 1/8" i.d. tube, 10 feet long, connecting thevacuum pump to a catheter, to aspirate 125 cc of blood while removing atypical thrombus. By reducing the tubing diameter to 1/16" i.d., theamount of blood aspirated was reduced to approximately 50 cc with noloss of efficacy. There is an obvious benefit to minimizing the amountof blood lost by the patient.

A valve may be located between the catheter and suction means to shutoff or regulate the vacuum level delivered to the catheter. Thisrepresents a convenient way for the cardiologist to regulate vacuumwithout having to have someone turn the pump on and off.

The collection bottle may be provided with a window, or clear portion,through which any clot collected in the filter may be visualized. Anaccess port located above the clot filter may be provided, through whichsaline or other washing solutions maybe directed onto the thrombus toimprove visualization and aid in discernment of clot fragments.

A push-pull transport system as described in U.S. Pat. No. 4,561,807,incorporated herein by reference, may be incorporated into the suctionmeans. The surfaces of all components in blood contact may be coatedwith an antithrombogenic material such as heparin complex, hirudin orother clot-inhibiting chemical. The purpose of such a coating is toensure that the collected clot came from the treated blood vessel andwas not formed from the liquid blood.

In comparison to some types of therapeutic catheters, such as balloondilatation catheters, the percutaneous aspiration catheter has arelatively large cross-section. This is required to prevent occlusion bythe aspirated thrombus. To assist in negotiating the catheter acrossrestrictions in a blood vessel the distal portion may be coated with alubricious or low friction coating such as polyvinylpyrrolidonehydrogel. Use of such a catheter in the coronary arteries of animalsubjects has reduced the difficulty in penetrating a thrombus. Oneadvantage of using a hydrogel coating for this purpose is thatantithrombotic material such as heparin may be incorporated into thehydrogel coating, providing both benefits with one coating application.The low friction-coating may also be placed on the inside of thecatheter lumen to reduce the possibility of the thrombus sticking withinit.

The internal flow cross-section of the catheter and connecting tubingmay be provided with a progressively increasing area to the thrombusfilter to prevent thrombus from plugging at any point.

Smooth surfaces and joints may be provided in the catheter andconnecting tubing to prevent thrombus from snagging and catching at anycorners or rough edges, preventing them from reaching the thrombusfilter.

The invention can perhaps be better understood by making reference tothe drawings. with reference to FIG. 1, schematic representation of abifurcated blood vessel 10 is depicted wherein a blunt tip catheter 12and guidewire 14 are inserted at the point of bifurcation showing thecatheter lodged at the point of bifurcation. FIG. 2 is a schematicrepresentation of bifurcated blood vessel 10 and an unconstrained angledtip-catheter 16 and guidewire 14, shown inserted at the point ofbifurcation and also showing the catheter lodged at the point ofbifurcation.

With reference to FIG. 3(a), constrained angle tip catheter 18 andguidewire 14 are inserted into bifurcated blood vessel 10. This showsthe smooth passage of the constrained angled tip catheter/guidewirethrough the point of bifurcation. FIG. 3(b) is a schematicrepresentation of a bifurcated blood vessel 10 having a constrainedangled tip catheter 18 in an alternative orientation and an insertedconstrained guidewire 14 at the point of bifurcation. Also shown is thesmooth transition of the catheter guidewire through the point ofbifurcation.

FIG. 4 comprises a schematic representation of a preferred arrangementof a complete percutaneous aspiration thrombectomy catheter systemaccording to the present invention. A constrained angled tip catheter 18has a guidewire 14 passing through the constrained distal tip of saidcatheter guidewire arrangement passing through guide catheter 20, whichin turn is contained within a hemostasis valve 22 through which thecatheter guidewire exits at the proximal end 24. Proximal to the exit ofthe catheter guidewire from the hemostasis valve is a guidewire exitport 26. The proximal end of the catheter is provided with atransitional connecting means 28 which is provided with an auxiliaryLuer port 30. The proximal end of the transitional connecting means isattached to a connecting tubing 32 which passes through a clamp 34before entering a collection bottle 36, which is provided with a filtermeans 38 to separate thrombus from blood which has been aspirated from apatient's artery. The outlet port of the collection bottle is providedwith additional connecting tubing 40 which passes through a hydrophobicbarrier filter 42 prior to entering the suction end of a suction means44.

FIG. 5(a) represents a preferred embodiment of a percutaneous aspirationthrombectomy catheter system according to the present invention, where atwo lumen configuration is depicted showing the catheter 18 having aguidewire 14 passing through a separate guidewire lumen 42 which isformed as part of the catheter 18. The proximal end of the catheterpasses through a hemostasis valve 22 and subsequently enters atransitional connection means 28 having an auxiliary Luer port 30, theproximal end of which connection means 28 is provided with connectingtubing 32.

A cross-sectional of the proximal portion of the catheter 18 is depictedin FIG. 5 (b) showing the internal guidewire lumen 46, which in thissection of the catheter is provided with a slit 48 for easy removal ofthe guidewire.

The cross-section of the distal portion of the catheter 18 is depictedin FIG. 5(c) showing the internal guidewire lumen 46, which in thissection of the catheter is not provided with a slit.

FIG. 6(a) is a schematic representation of the tip design for a singlelumen percutaneous aspiration thrombectomy catheter system according tothe present invention, showing the distal end of the catheter 18 havinga bent upward distal tip 50 and a thrombus entry opening 52 located inthe angled portion of the distal end 54. The bent up position of thedistal tip is provided with a guidewire opening 56 through which theguidewire 14 passes.

In FIG. 6(b) a top plan view of a schematic representation of the distalend of the catheter 18 shows the angled portion of the distal end 54,the thrombus entry opening 52, and the guidewire entry opening 56.

With reference to. FIG. 6(c) a lateral partly cross-sectional view ofthe distal-tip of the catheter 18 of FIG. 6(b) is depicted showing theangle orientation of the angled distal tip 50 and the location of theguidewire entry opening 56 prior to the formation of the bent tip in theupward position. The material of catheter 18 is sufficiently flexiblethat the distal tip 50 will lie flat prior to insertion of guidewire 14.However, if catheter 18 is made of more rigid material, the distal tip50 will be bent upward as in FIG. 6(a), without guidewire 14 present.

FIG. 6(d) is an end, distal view of the distal tip according to FIG.6(c) showing the catheter 18 and the location of the guidewire entryopening 56 prior to the tip being bent upward.

With reference to FIG. 7(a) a cross-sectional representation of a singlelumen catheter 18 is shown which depicts a necked down distal tip 58 andthe guidewire 14 passing through the distal end of said necked downdistal tip and exiting through the proximal guidewire exit opening 26.

With reference to FIG. 7(b) a longitudinal cross-section of the singlelumen design of the percutaneous aspiration thrombectomy catheter systemaccording to the present invention is shown depicting the catheter 18the necked down distal tip 58 of the catheter, and the thrombus entryopening 52.

FIG. 7(c) is a lateral view of the single lumen design of thepercutaneous aspiration thrombectomy catheter system and the necked downdistal tip 58, while FIG. 7(d) is a distal end view.

With reference to FIG. 8 a cross-sectional representation of a singlelumen off-set tip design for the percutaneous aspiration thrombectomycatheter system according to FIG. 5(a) is depicted showing the catheter18 guidewire 14 thrombus entry hole 52 and the distal tip having askewed orientation 60.

The embodiments of the invention shown in FIGS. 9(a) to 11(b) representvariations of the embodiment depicted in FIGS. 5(a) to 5(c). In FIG.9(a) catheter 18 comprises extended guidewire lumen 58, fixed concentricto which is barb 60. Barb 60 has a proximally extending section 62,which has one or more, preferably two, pointed members 63 to engagethrombus. Pointed members 63 extend slightly into opening 65, sufficientto be effective to retain thrombus as desired but not to block opening65.

Another arrangement is shown in FIGS. 10(a) to 10(c), where a cuttingblade 70 is positioned on blade holder 72 blade holder 72 is fixedlyconcentric to extended guidewire lumen 58. The purpose of blade 70 is tobisect large thrombi that might enter opening 65.

Barb 60, blade 70, and blade holder 72 are preferably fashioned fromrigid materials. Useful such materials include suitably rigid polymersand co-polymers and medically acceptable metals.

The embodiment shown in FIGS. 11(a) and 11(b) has a dilatation balloon80 concentrically positioned around catheter 82. Catheter 82 comprisesthree lumens, namely, suction lumen 84, guidewire lumen 86, andinflation lumen 88. Balloon 80 is in fluid communication with inflationlumen 88 by means of any conventional configuration or arrangement, suchas one or more inflation port 90.

Manufacture of the catheters herein, including the catheter of FIGS.11(a) and 11(b), is within the skill of any art skilled person. Forexample, the balloon can be manufactured and/or attached in conventionalmanner.

FIGS. 12-14 depict several alternative embodiments of the percutaneousaspiration catheter. In general, each of these embodiments have barbswhich are mounted inside a catheter near the distal end. Barbs providethe added advantage of trapping material within the catheter. Barbs alsoprevent pieces of thrombus from floating out of the catheter and furtherprovide an apparatus for removing emboli which are larger than thedistal end of the catheter. Variations on these embodiments include anembodiment with a flared distal end to the catheter (See FIG. 13). Theflared distal end has the advantage of providing a larger diametercapture opening. The flared distal end also allows room for theplacement of barbs within the tip without restricting the removal ofparticles. Any particles that are small enough to pass through thecatheter lumen will not be impeded by the barbs.

Another embodiment has an angled tip, where the angled tip provides aless traumatic tip and also creates a larger cross-sectional area to thedistal opening of the catheter (See FIGS. 12a and 14a). Anotherembodiment is disclosed that may be used over a guide wire (See FIGS.12a and 14a). Finally, an embodiment with a fixed guide wire tip at thedistal end of the catheter is disclosed (See FIG. 13). The fixed guidewire tip provides some of the advantages of a guide wire while alsoproviding a maximum cross-sectional open lumen for thrombus removal. Itis possible to make any of these embodiments in a fixed wire, over thewire, or no wire configuration. Further, any of these embodiments mayhave a straight tip, an angled tip, or a flared tip. All materials,dimensions, processes of manufacture, features, and advantagespreviously described may also apply to the following embodiments exceptas described hereafter.

FIG. 12a depicts an embodiment of the percutaneous aspiration catheterwhere barbs 110 are positioned within the distal portion of catheter 18and oriented such that the sharp part of the barb 110 is pointedproximally. Barbs 110 may be made separately and attached to theinterior of catheter 18 or integrally formed in a ring 115. Barbs 110may be machined into ring 115 by milling or laser cutting and arepreferably formed by electrical-discharge machining. It is veryimportant that barbs 110 be as sharp as possible. Therefore postpolishing or sharpening of barbs 110 may be preferred after barbs 110are machined into ring 11 5. Ring 115 may further be bent into anoncircular shape, as shown in FIG. 12b, where a reverse bend 118 in thecircumference of ring 115 may act as a guide wire retainer. Reverse bend118 retains guide wire 14 near the edge of the interior of catheter 18and therefore provides the maximum continuous cross-sectional area forthrombus to travel through catheter 18.

Ring 115 may be made of any medical grade metal, and is preferably aradio-opaque alloy, such as a platinum-iridium alloy consisting of 90%platinum and 10% iridium. As a radio opaque alloy, ring 115 may alsoserve as a marker band facilitating radiographic visualization. Ring 115may be mounted near the distal opening of catheter 18. Preferably ring115 is adhesively bonded to the interior of catheter 18. Adhesives thatmay be used include cyanoacrylates and epoxies.

Catheter 18 may be used with a guide wire 14, without a guide wire, orin a fixed wire configuration. Catheter 18 may have a single layer orplurality of layers. In a preferred embodiment catheter 18 may be madefrom three layers where the inner layer is made of PTFE and has a wallthickness of about 0.003 inches. The intermediate layer is a braid ofmetal or plastic filaments with a wall thickness of about 0.002 inches.The braid may have a continuous or variable pick count. The outer layeris a thermoplastic such as polyurethane with a wall thickness of about0.002 inches. When using catheters 18 with as larger as an outsidediameter of 0.039 inches, the flared tip may be as large as 0.052 inchesallowing barbs 110 to be bent inward 0.0065 inches without restrictingthe size of particles that may be drawn into catheter 18.

FIG. 13 shows another embodiment of the percutaneous aspiration catheterwhere the distal end of catheter 18 is larger in diameter than the bodyof catheter 18. This flared portion 125 provides a larger working areafor the suction end of catheter 18. Flared portion 125 preferably isformed by stretching the distal portion of catheter 18 over a hotmandrel. However, in embodiments where a layer of braid is incorporatedinto the construction of catheter 18, a separate flared portion 125 maybe constructed and adhesively attached to the distal end of catheter 18.

FIG. 13 also shows a fixed guide wire tip 120 which is mounted insidethe distal end of catheter 18 and extends out of the distal end. Guidewire tip 120 has a spring tip 14, as is commonly known in the art. Guidewire tip 120 may fit into a reverse bend 118 as in the embodiment shownin FIG. 12b. Guide wire 120 is adhesively bonded to catheter 18. Guidewire tip 120 provides guidance for catheter 18 and is helpful innegotiating the tortuous vasculature. Since guide wire tip 18 is bondedto catheter 18 near the distal end but does not extend proximally of thebond, guide wire tip 18 does not block most of the fluid path withincatheter 18. This guide wire tip configuration provides the ability tonegotiate tortuous vessels and still have the high suction capability ofembodiments of the percutaneous aspiration catheter that do not have awire.

Both of the embodiments of FIGS. 12a and 13 show an angled distal end ofcatheter 18 where the guide wire 14 or the fixed guide wire tip 120 ispreferably positioned to correspond to the distal-most portion of theangled end of catheter 18. As previously described, an angled tipprovides better advancement around corners and through bifurcatedvessels. FIG. 12a depicts the distal opening of catheter 18 having anangle θ with respect to a line parallel to the atherefore heter 18. Thedistal opening therefore must also be oriented at an angle θ withrespect to the axis of catheter 18 and must be from 0-90°. FIG. 14ashows yet another embodiment of the percutaneous aspiration catheterwhere the distal end of catheter 18 is flat and FIG. 14b depicts a sideview of the embodiment of FIG. 14a.

In use, barbed embodiments of the percutaneous aspiration catheter haveseveral added benefits. During normal aspiration barbs 110 provide asafety mechanism where embolus that is drawn into catheter 18 can notfloat out of the end of catheter 18. In addition, barbs 110 may beparticularly useful in removing particles which are larger than thediameter of catheter 18. In cases like these a portion of a large pieceof thrombus may be drawn into the end of catheter 18 and caught by barbs110. Even though the piece of thrombi is too large to flow throughcatheter 18 it can then be removed from the body by removing catheter18.

It will be further apparent to one skilled in this art that theimprovements provided for in the present invention, while described withrelation to certain specific physical embodiments also lend themselvesto being applied in other physical arrangements not specificallyprovided for herein, which are nonetheless within the spirit and scopeof the invention taught here.

I claim:
 1. A percutaneous aspiration catheter comprising:a catheterhaving a proximal end, a distal end, and a lumen therethrough; and aring mounted within the lumen of the catheter near the distal end, thering including a plurality of barbs that contact a portion of thematerial entering the catheter to reduce the likelihood that suchmaterial will re-exit the distal end of the catheter while being allowedto move toward the proximal end of the catheter, the ring furtherincluding a reverse bend suitable for forming a channel to act as aguide wire retainer.
 2. The percutaneous aspiration catheter of claim 1wherein the ring is made of a radio opaque material.
 3. The percutaneousaspiration catheter system of claim 1 wherein portions of the catheterare coated with an anti-thrombogenic coating.
 4. The percutaneousaspiration catheter system of claim 1 wherein the distal end of thecatheter is coated with a lubricious coating.
 5. The percutaneousaspiration catheter of claim 1 further comprising:a guide wire lumenwithin the catheter lumen.
 6. The percutaneous aspiration cathetersystem of claim 5 wherein a proximal end of the guide wire lumen isprovided with a slit for a portion of the length of the guide wire lumenfrom a proximal end of the guide wire lumen toward a distal end of theguide wire lumen, the slit allowing for the peeling of the catheter froma guide wire therein.
 7. The percutaneous aspiration catheter of claim 1further comprising:a wire tip attached to an internal surface of thecatheter lumen and extending beyond the distal end of the catheter.
 8. Apercutaneous aspiration catheter which comprises:an elongate catheterhaving a proximal end, a distal end and an aspiration lumen extendingtherethrough; means positioned within a distal end of the aspirationlumen the means comprising a ring including a reverse bend and barbshaving points that are oriented towards a longitudinal axis of theaspiration lumen and towards the proximal end of the catheter forengaging material that enters the aspiration lumen and preventing thematerial from re-exiting the distal end while allowing the material tomove toward the proximal end.
 9. The percutaneous aspiration catheter ofclaim 8, wherein the barbs are mounted on a ring that is positionedwithin the aspiration lumen at the distal end of the catheter.
 10. Thepercutaneous aspiration catheter of claim 9, wherein the ring includes areverse bend that forms a guide wire retainer in the aspiration lumen.11. An embolectomy method comprising:providing a catheter having anelongate body, a lumen therethrough, a distal opening, and barbs mountedwithin the lumen near the distal opening such that at least a portion ofmaterial entering the distal end of the catheter contacts some of thebarbs so that some material is prevented from exiting the distal end ofthe catheter while being allowed to move toward the proximal end of thecatheter; advancing the catheter through the vasculature until thedistal opening is adjacent a site to be treated; and providing suctionat a proximal opening of the catheter.
 12. The embolectomy method ofclaim 11 further comprising;catching material larger than the diameterof the lumen in the barbs; and removing the catheter from thevasculature while the material remains caught in the barbs.